Various presses and other equipment used for applying decals to substrates are known to the prior art. Some prior art equipment relies on silicone pads for pressing the decal to the substrate. For example, U.S. Pat. No. 5,300,170 (Donohoe) describes the use of a presshead in conjunction with a thin membrane of silicone rubber to apply a decal from a piece of carrier paper onto a substrate. As the presshead is lowered against the membrane, the membrane is deformed and pressed into contact with the decal. The dwell time of the presshead is set at a predetermined interval, after which the presshead is retracted and the membrane layer regains its shape, thus lifting the design layer away from its paper backing. The spent paper is then removed preparatory to another cycle. U.S. Pat. No. 5,142,722 (Kolb) describes the use of a silicon pad attached to a platen to attach a decal to furniture.
Many types of prior art equipment that apply decals to a substrate utilize decals that are mounted on a web of carrier paper. Thus, for example, U.S. Pat. No. 4,713,128 (Kerwin) and U.S. Pat. No. 4,369,082 (Kerwin) describe an apparatus for applying decals to articles. The decals are supplied on a web of carrier material. The machine consists of a supply spindle, a takeup spindle and a drive for moving the web from the supply spindle to the takeup spindle. A movable head presses the web and the decal against the surface to which the decal is to be applied. The machine is also provided with a brake and a sensor. The sensor activates the brake when the head is moving into position to press the decal to the surface, and releases it after the decal is applied to the surface.
Various methods are also known to the prior art for applying a decorative plastic film to a substrate. However, these methods have proven unsatisfactory to date for applying a decal to a foam substrate. For example, U.S. Pat. No. 4,409,275 (Samowich) and U.S. Pat. No. 4,329,386 (Samowich) describe a method whereby a decorative acrylic film is laminated to an acrylic foam. In a mass production situation, the acrylic film may be provided in rolls on silicon-coated release paper. The acrylic film is prepared by coating a lithograph with several coatings of a transfer emulsion which is allowed to dry. Next, the emulsion coated lithograph is soaked in water and allowed to dry. The acrylic film bearing the lithographic inks transferred from the lithograph is peeled off the soaked paper, and the ink side of the film is placed into contact with a foam substrate. A hot electric iron is then used to bond the film and foam together, simultaneously crushing the foam. The reference also notes that the foam may be crushed even further to provide crosslinking between the film and the foam.
While methods of this type may be suitable for some purposes, the bond achieved between the acrylic film and the foam substrate is not strong, and the film is therefore prone to peeling. Furthermore, it is undesirable when applying a decal to a finished article to have to crush the article in the vicinity of the decal in order to promote greater adhesion between the decal and the surface of the article. Finally, the aqueous immersion required by this type of method is messy and unsuitable for large scale processes.
It is thus an object of this invention to provide a solvent free method of applying a decal to a foam substrate.
It is a further object to provide a method for applying decals to foam substrates in which a strong bond is achieved between the decal and the substrate without having to physically modify the substrate.
In some prior art methods, the decal is provided on a film of plastic, such as Mylar, which is coated on one side with an adhesive. The film is then applied to a substrate by wetting or melting the adhesive and pressing the adhesive coated side of the film against the substrate. However, decals applied by this method tend to peel away from the substrate when they are exposed to moisture and shearing stresses. A further problem is that many of the films, such as Mylar, that have been used in methods of this type have poor abrasion resistance, and thus wear too quickly.
It is thus an object of this invention to provide a method for applying decals to a foam substrate in which the decal becomes one with the substrate, and is therefore resistant to peeling.
It is a further object of the present invention to provide a method for applying a decal to a foam substrate in which the resulting decal is resistant to abrasion.
Several prior art methods for securing foam articles and decals to the surface of a substrate rely on adhesives. U.S. Pat. No. 5,124,422, U.S. Pat. No. 4,713,412 (Czerepinski, et al.), U.S. Pat. No. 4,012,560, U.S. Pat. No. 3,931,444, U.S. Pat. No. 3,931,087, U.S. Pat. No. 3,903,057, U.S. Pat. No. 3,900,610, U.S. Pat. No. 3,893,982 and U.S. Pat. No. 3,886,126 are exemplary. However, the use of an adhesive for securing a decal to a foam surface has proven unsatisfactory, particularly in aqueous environments, and frequently results in peeling. Furthermore, most adhesives form only a weak bond between the decal and the foam surface.
It is thus an object of this invention to provide a method for applying a decal to a foam substrate that does not rely on adhesives.
These objects as set out above are achieved by the method of the present invention. Other advantages of the present invention will be apparent to those skilled in the art.